1. Field of the Invention
The invention relates to a thin film transistor (“TFT”) array substrate and a method of manufacturing the same, and more particularly, to a TFT array substrate having improved electric characteristics of an oxide semiconductor layer, and a method of manufacturing the thin film transistor array substrate.
2. Description of the Related Art
A liquid crystal display (“LCD”) is one of the most commonly used flat panel displays. The LCD, which includes two panels having a plurality of electrodes thereon and a liquid crystal layer interposed therebetween, controls the transmittance of incident light by applying voltages to the electrodes to rearrange liquid crystal molecules of the liquid crystal layer.
Among LCDs, the LCD of type provided with field-generating electrodes on two substrates is extensively used. Of the two substrates, the TFT array substrate includes a plurality of pixel electrodes provided in a matrix form. On the other substrate, a common electrode covers the entire surface of the substrate.
To realize images in the LCD, data voltages are applied to the respective pixel electrodes. To this end, thin film transistors (“TFTs”), which may bee three-terminal elements, for switching the voltages are connected to the applied to the respective pixel electrodes, and a plurality of wiring lines including gate lines and data lines is formed on the substrate. Signals for controlling the TFTs are transmitted through the gate lines, and the data voltages are transmitted through the data lines.
In the conventional LCD, the TFTs are classified into an amorphous silicon TFT and a polysilicon TFT according to the material of a channel portion of a switching element. The amorphous silicon TFT has charge mobility as low as approximately 0.5 squared centimeter per volt second (cm2/V-s), while achieving uniformity in electrical characteristics over a large-sized display device. On the other hand, the polysilicon TFT has charge mobility as high as approximately several hundred cm2/V-s, while achieving uniformity in electrical characteristics over a large-sized display device.